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Underground filters

I have to disagree. With glass bottom tanks, it is very easy to see what is
going on under the UGF. There are no air bubbles. The air stones are located
abotu an inch above the bottom of the lift tubes, so there isn't any way for
air to get under there anyway...
-JD

"atomweaver" wrote in message
...
Tynk wrote in
ps.com:
On Oct 9, 7:20?am, "jd" wrote:
Yeah, I can relate with the cleaning of the crud off th e plates, but
I only do that when I'm tearing atank down, which is hardly ever now.
Since I'm not doing commercial or research work any more, my tanks
are all recreational, and I don't have to tear them down unless there
is a good reason. I have tanks that have been going for 6 years
without a teardown, and they're rock solid.....
-JD

- Show quoted text -

As you and RM mentioned...the crud under the plates is my biggest
*con* when it comes to using them.
(Pay no attention JD to the troll tailing me...we are simply
discussing the pros and cons of them and he has to make it into
something it's not...sorry *for* him).
It's that crud that is basically a ticking time bomb. Often an area of
it becomes a toxic cess pool that can release a toxic gas bubble into
the tank.

I'm not big on fluid dynamics, but it seems totally plausible to me that
JD
was holding such a bubble in a static location (a "dead" corner?) under
the
UGF with the flow from his air pump, and the failure of the pump is what
allowed it to diffuse into the tank. THe rapidity with which his water
quality dropped (2 days, IIRC) indicates more than just normal metabolic
action of some fish in a heavily planted tank. JD's story may actually be
another indictment of UG filters, as that rapid drop in water quality
might
not have occurred if the UGF wasn't there, but I guess not enough is known
to say for sure.

I'm not sure I would call it ignorance, as I have spent alarge part of my
life designing large and small filtration units, and have an excelelnt
understanding of fliud dynamics and how filtration works.

In any case, while powerheads can increase the flow through an UGF, a
properly set up and maintained airstone can (and does) provide an excellent
water flow. as an example, in one of my tanks the air lift tubes creates a
little over 6" of lift (this is about average for my tanks). There are 6
lift tubes (it's a 125 gal), so summed together that is a lot of water flow.
Even though a power head may provide a bit more flow, more is not always
better, and I have ben very satisfied with the results at these flow rates.
I have played around with power heads, and unless I ma trying to create a
current in the tank, I don't see any significant advantage.
-JD

On Oct 9, 7:20?am, "jd" wrote:
Yeah, I can relate with the cleaning of the crud off th e plates, but
I only do that when I'm tearing atank down, which is hardly ever now.
Since I'm not doing commercial or research work any more, my tanks
are all recreational, and I don't have to tear them down unless there
is a good reason. I have tanks that have been going for 6 years
without a teardown, and they're rock solid.....
-JD
- Show quoted text -
As you and RM mentioned...the crud under the plates is my biggest
*con* when it comes to using them.
(Pay no attention JD to the troll tailing me...we are simply
discussing the pros and cons of them and he has to make it into
something it's not...sorry *for* him).
It's that crud that is basically a ticking time bomb. Often an area of
it becomes a toxic cess pool that can release a toxic gas bubble into
the tank.

I'm not big on fluid dynamics, but it seems totally plausible to me that
JD
was holding such a bubble in a static location (a "dead" corner?) under
the
UGF with the flow from his air pump, and the failure of the pump is what
allowed it to diffuse into the tank. THe rapidity with which his water
quality dropped (2 days, IIRC) indicates more than just normal metabolic
action of some fish in a heavily planted tank. JD's story may actually
be
another indictment of UG filters, as that rapid drop in water quality
might
not have occurred if the UGF wasn't there, but I guess not enough is
known
to say for sure.

DaveZ- Hide quoted text -

- Show quoted text -

The biggest problem is ignorance in how and what makes a UGF work, and
unless the bio load is light you need much more than an air pump to
get decent flow under the filter grates. The only way is with a decent
powerhead in place of the airstone or bubblers. Reverse flow works
fine too.............air powered tend to have dead spots, forced flow
(powerheads) do not tend to have dead spots.

I still have to disagree - the buildup of crud on the plates is actually the
bacteria colonies - they're a PITA to clean off the plates when a tank is
stripped down, but they don't cause any harm. While I have heard tales of
the "toxic gas buildup" caused by UGF, I've never experienced it, and
knowing the details of what it takes to cause it to happen, I find it very
unlikely (OK, practically impossible) for it to happen - even without
maintenance. No I know has experienced it either. Considering what it takes
for this scenario to occur in the natural world, it would be practically
impossible to hve it happen in a tank, even if you were trying to create it.
Also, the chemistry that is needed to cause the "toxic bubble" would kill
everything in the tank way before there was the possibility of enough toxic
gas developing to actually make a bubble....

Without maintenance, I can easily imagine an UGF getting matted an clogged
(actually, its the gravel that get clogged), but all that would really do is
make the filter inneffective - it wouldn't make the gravel any worse than it
would be without the UGF in place. Of course, as soon as the gravel was
vacuumed or stirred up, the filter would kick back in , and the bacteria
would repopulate the gravel pretty quickly.

I would also reiterate that a UGF is not meant to be the sole filter in a
tank. If that is how you were using them, I can understand why you would
have had problems with them. (even with a sponge filter, all you are really
providing is bio filtration - nothing else). Another factor that may be
causing you problems is the size of your tanks. Bigger tanks are always more
stable than small tanks, and a lot of the filter advances that have occurred
over the past decade or so relate to trying to make smaller tanks more
stable, making possible to have a larger carrying capacity (more fish per
gallon), and making it easier to keep both fish and plants in the same tank.
20 years ago, all of these were labour intesive, and prone to error - the
smaller the tank, the more likely it would be for an error to occur, and
quickly spiral out of control. The new technologies have made it much easier
to keep small tanks with lots of fish and plants, but they do not necesarily
perform better than some of the older technologies - it really depends on
what you want from your tank.

powerheads and high throughput canister filters are not very good for a pond
or lake setup - for fish that do not live in an environement with currents.
UGF and low-throughput filters are much better for these tanks, as they can
be run wothout creating alot of current. They ca move a lot of water through
the filter media (gravel) without introducing a current to the overall tank.

For a current environment (stream or river), powerheads and high throughput
filters are great - you want all of that flow to create the currents that
the fish "expect". In those environments, an UGF provides some ectra
buffering of the biological filtration (I am a proponent of the "more is
better" school of thought on biofilters).

I must admit that I have never bothered to keep small tanks (I consider a
5gal to be a fry tank). I would suspect that on the tiny 1,2,3 gallon tanks,
an UGF probably wouldn't make a huge difference - by the time you had a deep
enough gravel bed (2" min.), you would have taken up a lot of the tank
volume with gravel. In those tiny tanks, keeping the water volume as high as
possible is probably the most critical thing, so exxternal filtration would
probably be the way to go . Not only would the filtration not be taking up
tank volume, it would be adding ot hte total water volume by providing an
exterior "resevoir" in the filter itself....

"Tynk" wrote in message
ps.com...
On Oct 9, 7:20?am, "jd" wrote:
Yeah, I can relate with the cleaning of the crud off th e plates, but I
only
do that when I'm tearing atank down, which is hardly ever now. Since I'm
not
doing commercial or research work any more, my tanks are all
recreational,
and I don't have to tear them down unless there is a good reason. I have
tanks that have been going for 6 years without a teardown, and they're
rock
solid.....
-JD

- Show quoted text -

As you and RM mentioned...the crud under the plates is my biggest
*con* when it comes to using them.
(Pay no attention JD to the troll tailing me...we are simply
discussing the pros and cons of them and he has to make it into
something it's not...sorry *for* him).
It's that crud that is basically a ticking time bomb. Often an area of
it becomes a toxic cess pool that can release a toxic gas bubble into
the tank.
Yeah, I know that sounds pretty stupid, but it does happen and it can
kill fish.
Now that doesn't mean they're all like that, as proper maintenance
plays a huge part. However, in reality not too many are.
Another *con* for me is when there is a breakdown (either pump
failure, clog, or powerhead failure) and it can turn into a bigger
problem.
I wonder if it has to do with the crud under the plates in addition to
dying bacteria?
Maybe it's because the canister isn't actually inside the tank and a
malfunctioning canister is somewhat contained.
I like the canisters that also have a biowheel.
For folks who don't want a lot of added noise in the same room as a
large tank, such as a tv room or family room, etc...it's a better
choice than an UGF.
If noise and less equipment running isn't a concern, and they're
properly maintained, then sure...they have their purpose. I can't deny
them that.
I just find them to be a pain in the butt, and there to be better,
less noisy options out there.
I remember years ago taking out the UGF in my 29g (back then my tanks
were either run by an UGF or sponge filter or both), and taking that
first step away from them.
It was scary for me, as well as for many long time hobbyists.
After realizing there was no downfall, no *con* without it, only good
things...I've never used since. I actually toss out the new ones that
come with tank set ups, and replace it with a power filter.
Heck, even those have a long way too!
Now they have mini power filters for tiny 1g tanks.
Filtration has come a long way recently, and I just wish they would
have done it years ago. = )
When I had angels and betta spawns going, those mini power filters on
the juvie male betta male tanks would have been so usefull!

"Larry Blanchard" wrote in message
news
On Tue, 09 Oct 2007 18:18:08 -0500, Reel McKoi wrote:
Depending on how many juveniles you have and what you can afford. These
little mini filters cost $5.99 each! =:-O

I use something called "dispose-a-filter" in my fry tank. They come in a
pack of 2. I don't remember the price, but they weren't expensive. I got
them at Petsmart.

I assume they're powered by air?!?!?!
You're supposed to replace them every 4 weeks, but that's just because of
the carbon, which I sometimes take out. In any case, after I use the pack
of 2 for 8-10 weeks, the fry are large enough that I can use an Aquaclear
with a sponge over the intake.

I just use sponge filters with fry until they're large enough to be
comfortable with the small Aquaclears. Aquaclears are too large for Betta
bowls or tanks. A mini Azoo at $5.99 for each Betta tank can get costly
when you breed and raise them.
--

"jd" wrote in
:
"atomweaver" wrote in message
I'm not big on fluid dynamics, but it seems totally plausible to me
that JD
was holding such a bubble in a static location (a "dead" corner?)
under the
UGF with the flow from his air pump, and the failure of the pump is
what allowed it to diffuse into the tank. The rapidity with which
his water quality dropped (2 days, IIRC) indicates more than just
normal metabolic action of some fish in a heavily planted tank. JD's
story may actually be another indictment of UG filters, as that rapid
drop in water quality might
not have occurred if the UGF wasn't there, but I guess not enough is
known to say for sure.

I have to disagree. With glass bottom tanks, it is very easy to see
what is going on under the UGF. There are no air bubbles. The air
stones are located abotu an inch above the bottom of the lift tubes,
so there isn't any way for air to get under there anyway...
-JD

*shrug* Perhaps a UGF dead spot holds the toxics dissolved in water, then.
My own experience with UGFs is limited, and had poor results compared to
modern options.... But, people used UGFs for decades, and they kept FW
tanks just fine. It seems you can make UGFs work for you. Good on ya',
then. HOBs and cannisters are IME much easier, safer and effective, but if
you've got something that works, too, keep at it. Still, a big water swing
in two days with an active operating cannister filter is an indication that
something more was going on in your tank. Big die-off in the UGF bacterial
colony itself, maybe? Once you stop flowing water in the UGF, that
underplate area could go anaerobic pretty quickly, kill off your bacteria
colony, and then diffuse into the tank from there. (another) *shrug*...
like I said, not enough known to say for sure.

actually, the most probably cause is the fact taht having the UGF lets me
"overload" the system pretty heavily - that is one of hte reaswons I like it
so much. What was really interesting was that when the canister tanked, the
water quality didn't really change, but when the UGF tanked, there was a
pretty fast crash. My guess is that the difference in surface area for
bacteria to love on is what really make sthe diff - the canister has a lot
less surface area for bacterial colonies than the huge gravel bed (a 125
tank, 2-4 inches of gravel, as opposed to a (roughly) 1.5 gallon canister.

I agree that UGFs aren't for evreyone, but (like almost any tool that can
work) eliminating them out of hand is foolish. If you've tried them, and not
had luck, they obviously aren't for you. My main point was that they have a
bad rep that, in my decades of experience, is undeserved. When I work with
newbies to set up tanks, I always start them out with a UGF as a component
of their filtration system. If they decide they don't like it, they can
always simply pull out the lift tubes. The space under the plates will fill
pretty quickly with loose gravel (no caps on the lift tube holes), and the
only real difference is that there is a bit of extra plastic inthe tank...

-

"atomweaver" wrote in message
...
(top-posting repaired...)

"jd" wrote in
:
"atomweaver" wrote in message
I'm not big on fluid dynamics, but it seems totally plausible to me
that JD
was holding such a bubble in a static location (a "dead" corner?)
under the
UGF with the flow from his air pump, and the failure of the pump is
what allowed it to diffuse into the tank. The rapidity with which
his water quality dropped (2 days, IIRC) indicates more than just
normal metabolic action of some fish in a heavily planted tank. JD's
story may actually be another indictment of UG filters, as that rapid
drop in water quality might
not have occurred if the UGF wasn't there, but I guess not enough is
known to say for sure.

I have to disagree. With glass bottom tanks, it is very easy to see
what is going on under the UGF. There are no air bubbles. The air
stones are located abotu an inch above the bottom of the lift tubes,
so there isn't any way for air to get under there anyway...
-JD

*shrug* Perhaps a UGF dead spot holds the toxics dissolved in water,
then.
My own experience with UGFs is limited, and had poor results compared to
modern options.... But, people used UGFs for decades, and they kept FW
tanks just fine. It seems you can make UGFs work for you. Good on ya',
then. HOBs and cannisters are IME much easier, safer and effective, but
if
you've got something that works, too, keep at it. Still, a big water
swing
in two days with an active operating cannister filter is an indication
that
something more was going on in your tank. Big die-off in the UGF
bacterial
colony itself, maybe? Once you stop flowing water in the UGF, that
underplate area could go anaerobic pretty quickly, kill off your bacteria
colony, and then diffuse into the tank from there. (another) *shrug*...
like I said, not enough known to say for sure.

"jd" wrote in
:
"atomweaver" wrote in message
I'm not big on fluid dynamics, but it seems totally plausible to me
that JD
was holding such a bubble in a static location (a "dead" corner?)
under the
UGF with the flow from his air pump, and the failure of the pump is
what allowed it to diffuse into the tank.
I have to disagree. With glass bottom tanks, it is very easy to see
what is going on under the UGF.
Still, a big water
swing
in two days with an active operating cannister filter is an
indication that
something more was going on in your tank. Big die-off in the UGF
bacterial
colony itself, maybe? Once you stop flowing water in the UGF, that
underplate area could go anaerobic pretty quickly, kill off your
bacteria colony, and then diffuse into the tank from there.
(another) *shrug*... like I said, not enough known to say for sure.

actually, the most probably cause is the fact that having the UGF lets
me "overload" the system pretty heavily - that is one of the reasons
I like it so much.

Understood. You can crowd the tank, since you've got more surface area
of gravel with active bacteria.
What was really interesting was that when the
canister tanked, the water quality didn't really change, but when the
UGF tanked, there was a pretty fast crash.

WHy is that interesting?
My guess is that the
difference in surface area for bacteria to love on is what really makes
the diff - the canister has a lot less surface area for bacterial
colonies than the huge gravel bed (a 125 tank, 2-4 inches of gravel,
as opposed to a (roughly) 1.5 gallon canister.

Right. So when you do go down, you've got more biomass in bacteria dying
off, _and_ more fishies making number 2. Which is the greater factor in
water degradation? Dunno, myself...
I agree that UGFs aren't for evreyone, but (like almost any tool that
can work) eliminating them out of hand is foolish. If you've tried
them, and not had luck, they obviously aren't for you. My main point
was that they have a bad rep that, in my decades of experience, is
undeserved.

Bad rep? No. They have advantages and disadvantages, and for many in
the hobby, those trade-offs don't line up with their preferences. Given
what you've said about over-stocking a tank, I'd guess it has to do in
part with system stability when the power goes off.
When I work with newbies to set up tanks, I always start
them out with a UGF as a component of their filtration system.

I hope you tell them about how easy it is to over-stock the tank... If
they (like me) have blackouts from time to time, its an advantage to have
tanks which can sustain themselves for a while, or at least know that
once the power goes off, you've got a situation on your hands.
If they
decide they don't like it, they can always simply pull out the lift
tubes. The space under the plates will fill pretty quickly with loose
gravel (no caps on the lift tube holes), and the only real difference
is that there is a bit of extra plastic inthe tank...

Don't you use some sort of a screen mesh to keep the gravel above the
plenum?

They are still aound, but not actual accepted any more. They got a lot of bad press if fanmcier (and abundant added expensive) alternates came out. Undergravel filters are still a abundant bargain advantage for drastically increasing your biofiltration capacity.